We are running 3cx on a WHS box connected to a Netgear UTM. All phones are IP phones connected to a Netgear POE switch. VOIP provider is Nexvortex. Have been successfully run this setup for several years. The attempt to upgrade to v10 caused one way audio initially which I was told a network issue related to a security feature. I was able to fix this by turning on the Stun server. I was later told by Mark Shehan with ABC123IT that 3cx was expecting audio on one port and it was being received on another. So, I assume that I will have to change the port forwarding on my router to fix this.
The dropped calls were only external calls. Internal calls seemed to work fine.
I understand that these are probably network related but they are also related to going to v10 from v9.